Treating cellulose-ester products



[UNITED STATES DER W. PHILLIPS, OF EAST ORANGE, NEW JERSEY.

TREATING CELLULOSE-MTER PRODUCTS.

Specification of Iletters Patent. I

Patented Apr. 4,1922.

No Drawing. Original application filedv March 24, 1921, SerialNo.455,183. Divided and this application filed January 3, 1922. Serial No.526,767.

Cellulose-Ester Products, of which the fol-- lowing is a specification.-

This invention relates to cellulose esters and particularly tonitrocellulose products of relatively low viscosity and a process formaking the same. Heretofore the viscosity of nitrocellulose compositionswhere important has been controlled by the selection and preparation ofthe raw materials. and by the treatment during the process of nitration.In many applications, as for example, in making smokeless powder, butlittle, if any, attention is given to the matter of viscosity and theresult is normally a product having a relatively high viscosity. Incertain other applications, as for example, in leather dopes, the matterof viscosity is of importance. But to attain the desired degree ofviscosity by the selection of materials and controlling theirpreparation and nitration introduces considerable difficulty in thecontrol of the processes employed and also more or less efiectsthe yieldof the processes. In speakin here of the viscosity of nitrocelluloseproducts, which are often solids,

what is meant is the viscosity of doughs and solutions which result fromthe incorporation of suitable solvent mixtures with the nitrocelluloseproducts. I

I have discovered that after nitration a determined degree of permanentlower viscosity may be imparted to the product.

In carrying out my invention I employ-'- (1) nitrocelluloses of varyingdegrees of nitration, and (2) nitrocellulose products which have beenmade by gelatinating the nitrated cellulose by means of solvents orgelatinating agents, and wherein the nitrocellulose has lost its fibrousform and has become a gel. In the commercial forms of the latter thegel, while usually a solid, still retains some of the solvents orgelatinating agents originally incorporated with it. Ex amples of thisgroup are celluloid, smokeless powders, nitrocellulose films andnitrocellulose coatings used among other urposes, to imitate leather.These pro ucts may and usually do contain other ingredients thanresidual solvents and gelatinating agents, such asoils, pigments,stabilizers or antacids, coloring matters, diluents, gums, and manyother substances incorporated to impart desired characteristics, orresulting from impurities or reactions among the in- 'gredients. I havediscovered that by sub-. jecting nitrocellulose and such gelatinatednitrocellulose products to heat under proper conditions the viscositywill be permanently lowered. The process may be carried out by-(a) dryheating, or by heating the materials in the presence of water or other,nonsolvent liquid or llquid having low sol 100 C. to 1 l0 C. or highercorresponding to the steam pressure maintained. In some instances I havemaintained a lower temperature for a greater duration of timeand haveobtained a product of similar viscosity to that obtained by maintaininga higher temperature for a lesser time of treatment. For example, Iheated three" samples of smokeless powder and determined the viscosityof equally concentrated solutions of each in a solvent mixture'composedof ethyl acetate and benzol, One sample was heated at the temperature ofand submerged in boiling water for about eighteen hours and at the endof that time-it had attained approximately the same viscosity asanothersimilar sample which was heated while submerged in Water in an autoclaveat approximately one half hours a viscosity lower than either of theother two. Thus by a suitableselection of temperature range and durationof treatment it is possible by procedure (6) to control the reduction inviscosity of the Iii-J trocellulose quite accurately.

By 'dry heating according to procedure (a) 'in' air,'or in the presenceof indifferent gases which is safer from the view point ofconflagrations, I find that the nitrocellulose and its products are soaltered that the viscosity of the colloid solutions and doughssubsequently made with solvents from a product so treated is verygreatly lowered as compared with a similar solution or dough made fromthe original untreated material. For, example, a solution of anitrocellulose or nitrocellulose product which has been for two hourssubjected to a temperature of 120 C. will be found to be much more fluidthan a similar solution of equal concentration made from the untreatedmaterial. If heated for three hours at a temperature of 130 C. theviscosity will be found to be lower than that of a similar materialwhich has never been subjected to this temperature.

By my process it is possible to prepare from the nitrocelluloses andnitrocellulose products described products which have a very low degreeof viscosity and this alteration is permanent so that the material inits various commercial solutions and doughs shows a decreased viscosityadapting it for a wide variety of uses to which it could not hitherto beput. Smokeless powder subjected to any of the above treatments loses aconsiderable part of its residual solvents so that its solvent contentis reduced below the normal solvent content of smokeless powder and itbecomes dry in appearance treating the ester product to gelatinate it.

and then heating the gelatinated ester product in the presence of anon-solvent fluid until the desired degree of viscosity is attained.

3'. The process of lowering the viscosity of a gelatinated celluloseester product which consists in heating the same in the presence of anon-solvent liquid until the desired degree of viscosity is attained.

a 4. The process of lowering. the viscosity of smokeless powder whichconsists in heating the same-1n the presence of a non-solvent liquiduntil the desired degree of viscosity is attained.

5. The process of reducing the viscosity of a gelatinated celluloseester product consisting in heating the same in a non-solvent medium toa temperature between that at which substantial change in viscositytakes place and the temperature at which the compound in question isdecomposed.

6. A composition of matter comprising smokeless powder material havingits viscosity reduced below the lowest normal viscosity of smokelesspowder and its solvents reduced belowthe lowest normal solvent contentof the smokeless powder'so that said smokeless powder is brittle andrelatively incompressible without breaking an is adapted in solution toserve asa lacquer or spray. v

7. The process of lowering the viscosity of a gelatinated celluloseester product by heating the same in solid form at a temperature above100 C. until the desired lower degree of viscosity is attained.

8. The process of lowering the viscosity of smokeless powder whichconsists in heating it in solid form in a medium which will not readilysupport its combustion, until the desired lower degree of viscosity isattained.

9. The process of producing a gelatinated cellulose ester product of lowviscosity comprising making a cellulose ester of relatively highviscosity, treating said ester with a solvent to gelatinate it, andsubsequently treating said gelatinated cellulose ester in a non-solventmedium to lower its viscosity a desired degree below said originalVlSCOSItY.

10. The process of producing a gelatinated cellulose ester product oflowviscosity comprising treatiin a cellulose ester of relatively highvlscosity with a solvent to, gelatinate it, and subsequently treatingsaid gelatinated cellulose ester in a non-solventmedium to lower itsfinal viscosity a desired degree below its original viscosity.

. 11. The process of producing a gelatinated cellulose ester product oflow viscosity comprising subjecting a relatively highlyviscuous-cellulose ester gelatinated by treatment with a solvent totreatment in a non-solvent medium to lower its final viscosity a desireddegree below-its original viscosity.

ALEXANDER W..PHILLIPS.

